The neuropathology core will provide diagnostic services as will as serving as a central source of pathological specimens for the research projects. The core will handle all neuropathological specimens derived from subjects included in the clinical core. Close linkage will be maintained with the clinical core so that clinical information is conveyed with pathological specimens and so that diagnostic information and results of specialized research studies are available to clinical researchers. Autopsy brains will be obtained as quickly as possible following death by the Project Leader will the help of an on-call autopsy technician and pathology resident. The brains will be sampled while fresh for diagnosis, electron microscopy, and formalin fixation for immunohistochemistry. The remaining brain will be placed in a -70o C freezer for future research studies. The Project Leader and Co-Leader will establish priority for distribution of this tissue and for special protocols to be performed on the fresh tissue as needed.